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    function fn(a,c){
       console.log(a);// f a(){}
       var a = 123;
       console.log(a) // 123
       console.log(c) // fun c(){}
       function a(){}
       if(false){
          var d = 678;
       }
       console.log(d); //undefined
       console.log(b); // undefined
       var b = function (){}
       console.log(b) // f (){}
       function c(){}
       console.log(c) // f c(){}
   }
   fn(1,2)
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